docs: highlight and add details to Getting involved page

[hajjimo]

Creating this issue based on feedback from Don of Fynbos.

The Getting involved page is currently under Resources and should be placed higher in the navigation. Don suggested making it a top-level item or under Overview. Each section of the page should have more detailed steps where applicable. For example, instead of just linking to the repo in the contributing code section, provide a step-by-step list to help users find good first issues to contribute to.

[melissahenderson]

To discuss as a team. Also, I need to check with Ioana on a few things before we do anything with this issue.

[melissahenderson]

Chatted with Ioana over Slack today and she doesn't have revamping the Get Involved pages on her to-do list for this year.

We can use the Rafiki page to try out adding more detailed steps and if it works well, we can do it to the other Get Involved pages. I'm not ready to move the pages out of Resources, though (not yet anyway).